The present invention relates to high voltage insulators. More specifically, the present invention is concerned with a high-voltage insulator made of composite materials. The present invention is also concerned with a method of manufacturing such a high-voltage composite insulator.
Typically, high-voltage insulators include an elongated core made of an electrically insulating material such as porcelain or fiberglass. The ends of the elongated core are provided with respective metal fittings while the length of the core is covered with a polymeric outer sheath defining convolutions to increase the creepage distance between the metal fittings.
These conventional high-voltage insulator suffer many drawbacks. For example, when the elongated core is made of porcelain, it is relatively heavy and brittle. On the other hand, when the elongated core is made of a fiberglass rod, the resulting insulator is relatively weak when torsional forces are applied thereto since the fibers are longitudinally oriented.
Furthermore, in both cases, since the polymeric material forming the outer sheath and the material forming the elongated core are not chemically compatible, the interface between these two elements is purely mechanical and may thus be broken. It is also to be noted that failure of the high-voltage insulator would occur should water infiltrate the insulator through the interface between the outer sheath and the elongated core.
A third drawback of conventional high-voltage insulators is that it is not usually possible to visually determine when the elongated core of the insulator has been broken due to excessive forces applied thereto. Indeed, since the elongated core is covered by an outer sheath usually made of a relatively flexible material, the core may break without breaking the outer sheath.
An object of the present invention is therefore to provide an improved high-voltage composite insulator.
More specifically, in accordance with the present invention, there is provided a high-voltage composite insulator comprising:
first and second fittings; the first and second fittings being spaced apart along a longitudinal axis;
a spacer positioned between the first and second fittings;
a resin impregnated fiber core wound onto the first and second fittings and onto the spacer; the core including fibers and a resin matrix; and
an outer sheath mould onto the resin impregnated fiber core; the outer sheath being made of a material chemically compatible with the resin matrix of the core to thereby create a chemical link between the resin impregnated core and the outer sheath.
According to another aspect of the present invention, there is provided a method of making a high-voltage composite insulator comprising:
providing a first fitting;
providing a second fitting;
providing a spacer;
mounting the spacer between the first and second fittings;
winding fibers impregnated with a resin matrix onto the first and second fittings and onto the spacer to form a core;
moulding an outer sheath onto the core; the outer sheath being made of a composite material that is chemically compatible with the resin matrix of the core; and
co-curing the core and the outer sheath to create a chemical link between the core and the outer sheath.
According to yet another aspect of the present invention, there is provided a high-voltage composite insulator comprising:
first and second fittings; the first and second fittings being spaced apart along a longitudinal axis; each the first and second fittings including an anchoring portion having a generally rounded geometric shaped cross-section;
a spacer mounted between the first and second fittings;
a resin impregnated fiber core wound onto the first and second fittings and onto the spacer; and
an outer sheath mould onto the resin impregnated fiber core.
According to a final aspect of the present invention, there is provided a high-voltage composite insulator comprising:
first and second fittings; the first and second fittings being spaced apart along a longitudinal axis; one of the first and second fittings having a relatively thin wall portion;
a spacer mounted between the first and second fittings;
a resin impregnated fiber core wound onto the first and second fittings and onto the spacer; and
an outer sheath mould onto the resin impregnated fiber core;
wherein the relatively thin wall portion of one of the first and second end fittings is generally weaker than both the resin impregnated fiber core and the outer sheath, thereby creating a mechanical fuse.
Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.